JP2010025035A - Valve timing control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To relatively quickly learn a holding duty value for maintaining an actual ignition timing advance quantity of a hydraulic variable valve timing mechanism in a present state position. <P>SOLUTION: A control duty value for controlling a hydraulic control valve of the hydraulic variable valve timing mechanism, is determined by adding a feedback correction quantity based on a deviation between a target ignition timing advance quantity and the actual ignition timing advance quantity to the holding duty value. In variable valve timing control, whether or not the changing direction of the actual ignition timing advance quantity is changed in the direction separating from the direction approaching the target ignition timing advance quantity, is monitored, and when detecting that the changing direction of the actual ignition timing advance quantity changes to the direction separating from the target ignition timing advance quantity, learning of the holding duty value is performed. Thus, the holding duty value can be learnt without conventionally waiting until a state of not respectively changing in the target ignition timing advance quantity and the actual ignition timing advance quantity, continues for a predetermined time, and the holding duty value can be relatively early learnt. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a valve timing control device for an internal combustion engine having a function of learning a holding control amount for maintaining an actual valve timing at a current position.

  2. Description of the Related Art There is known a variable valve timing control device that changes an opening / closing timing (valve timing) of at least one of an intake valve and an exhaust valve of an internal combustion engine (engine) according to an engine operating state. In general, in a hydraulic variable valve timing control device using hydraulic pressure as a drive source, the hydraulic pressure supplied to the variable valve timing mechanism is adjusted by duty-controlling the hydraulic control valve (OCV), so that the engine crankshaft and cam The valve timing is changed by changing the rotational phase difference from the shaft.

  By the way, the control duty value of the hydraulic control valve can be calculated based on the deviation between the target valve timing and the actual valve timing calculated based on the engine operating state and the holding duty value (holding control amount). Here, the holding duty value is a duty value when the displacement speed of the valve timing becomes 0, that is, a duty value for maintaining the current valve timing.

In general, the holding duty value varies depending on manufacturing tolerances of the variable valve timing mechanism and the hydraulic control valve, changes with time, oil temperature, engine speed, and the like. If the holding duty value changes, the actual valve timing cannot be controlled with high accuracy, and the accuracy of the variable valve timing control may be reduced. For this reason, it is necessary to learn the holding duty value in accordance with the engine state at that time. As such a learning technique, there is a technique disclosed in Patent Document 1, for example. In Patent Document 1, when the deviation between the target valve timing and the actual valve timing is equal to or greater than a predetermined value and the state in which the target valve timing and the actual valve timing do not change continues for a predetermined time, the control duty value is set. A technique for learning as a holding duty value is described.
JP-A-11-36905

  However, in Patent Document 1, since the learning execution condition is that the state in which the target valve timing and the actual valve timing do not change each continues for a predetermined time, for example, the responsiveness of the variable valve timing mechanism decreases for some reason. In such a case, the actual valve timing is delayed to converge to the target valve timing, and the learning execution condition is delayed to be satisfied. Due to the mismatch between the actual valve timing and the target valve timing, There is a risk of problems such as insufficient torque. In addition, if the learning execution condition is established later, the frequency at which the learning execution condition is established is reduced accordingly, so the learning frequency of the holding duty value is reduced and the learning accuracy of the holding duty value is reduced. There is also a problem.

  In view of the above problems, an object of the present invention is to provide a valve timing control device for an internal combustion engine that can learn a holding control amount (holding duty value) for maintaining the actual valve timing at the current position relatively early. .

  Therefore, the invention according to claim 1 of the present application controls a variable valve timing mechanism that changes the valve timing on the intake side and / or the exhaust side of the internal combustion engine using hydraulic pressure as a drive source, and the hydraulic pressure that drives the variable valve timing mechanism. Hydraulic pressure control means, target valve timing setting means for setting target valve timing based on the operating state of the internal combustion engine, and actual valve timing detection means for detecting actual valve timing (hereinafter referred to as “actual valve timing”) A control amount calculating means for calculating a control amount of the hydraulic control means based on a deviation between the target valve timing and the actual valve timing and a holding control amount for maintaining the actual valve timing at a current position. The learning means for learning the amount is an actual value detected by the actual valve timing detecting means. It is determined whether or not a learning execution condition for learning the holding control amount is satisfied based on the change timing of the timing, and the holding control amount is learned when it is determined that the learning execution condition is satisfied. It is what I did.

  In this way, it is determined whether or not the learning execution condition is satisfied based on the change direction of the actual valve timing, and the holding control amount is learned when it is determined that the learning execution condition is satisfied. For example, it is possible to learn the holding control amount without waiting until the target valve timing and the actual valve timing do not change for a predetermined time, and it is possible to learn the holding control amount relatively early. Become. As a result, the period during which the deviation between the target valve timing and the actual valve timing is large is shortened, so that problems such as torque shortage and emission deterioration caused by the mismatch between the actual valve timing and the target valve timing can be reduced. . Moreover, it is possible to increase the accuracy of variable valve timing control by increasing the learning frequency / learning accuracy of the holding control amount.

  Further, as in the invention according to claim 2, as the learning execution condition, it is determined whether or not the actual valve timing has changed in a direction in which the deviation between the target valve timing and the actual valve timing increases, and the determination is affirmed. It may be determined that the learning execution condition is satisfied. If the holding control amount of the hydraulic control valve is not set correctly, the actual valve timing changes in a direction that increases the deviation between the target valve timing and the actual valve timing. Therefore, the actual valve behavior is detected and held. It is preferable to learn the control amount.

  Further, as in the invention according to claim 3, as the learning execution condition, after the deviation between the target valve timing and the actual valve timing is reduced, has the change direction of the actual valve timing changed in a direction in which the deviation increases? If the determination is negative and the determination is affirmative, it may be determined that the learning execution condition is satisfied. In this way, it is possible to more accurately detect a state in which the holding control amount is not set correctly.

  Further, as in the invention according to claim 4, it may be determined whether the actual valve timing is changed as at least one of the learning execution conditions. Further, as in the invention according to claim 5, the change direction of the actual valve timing may be determined based on whether the change speed of the actual valve timing is a positive value or a negative value.

  Further, as in the invention according to claim 6, the learning means may learn and correct the holding control amount based on the control amount calculated according to the deviation between the target valve timing and the actual valve timing. Thereby, the learning accuracy of the holding control amount can be increased.

Hereinafter, an embodiment in which the best mode for carrying out the present invention is applied to an intake side variable valve timing control device will be described.
First, the configuration of the intake side variable valve timing control device will be described with reference to FIGS.

  As shown in FIG. 1, in an engine 11 that is an internal combustion engine, power from a crankshaft 12 is transmitted to an intake side camshaft 16 and an exhaust side camshaft 17 via sprockets 14 and 15 by a timing chain 13. It is like that. However, the intake side camshaft 16 is provided with a variable valve timing mechanism 18 that adjusts the advance amount of the intake side camshaft 16 with respect to the crankshaft 12.

  A cam angle sensor 19 is installed on the outer peripheral side of the intake cam shaft 16, while a crank angle sensor 20 outputs a crank angle signal pulse at every predetermined crank angle on the outer peripheral side of the crank shaft 12. Is installed.

  On the other hand, as shown in FIG. 2, the cam angle sensor 19 is disposed so as to face the outer peripheral portion of the signal rotor 71 of the cam shaft 16. The cam angle signal is output every 180 ° CA as the signal rotor 71 (intake side camshaft 16) rotates. Crank angle determination and cylinder determination are performed by counting pulses of the crank angle signal of the crank angle sensor 20 with reference to the cam angle from which the cam angle signal is output from the cam angle sensor 19.

  The output signals of the cam angle sensor 19 and the crank angle sensor 20 are input to an engine control circuit 21 (hereinafter referred to as “ECU”). The ECU 21 calculates the actual valve timing of the intake valve, and the crank angle sensor 20. The engine speed is calculated from the output pulse frequency (pulse interval). In addition, output signals from various sensors (intake pressure sensor 22, water temperature sensor 23, throttle sensor 24, etc.) that detect the engine operating state, and output signals from the ignition switch 25 and timer 26 are also input to the ECU 21.

  The ECU 21 performs fuel injection control and ignition control based on these various input signals, and also performs variable valve timing control, and sets the actual valve timing of the intake valve (actual advance angle of the intake camshaft 16) as the target valve. The hydraulic pressure for driving the variable valve timing mechanism 18 is feedback-controlled so as to coincide with the timing (target advance amount). The oil in the oil van 27 is supplied to the hydraulic circuit of the variable valve timing mechanism 18 from the oil pump 28 via the hydraulic control valve 29, and the hydraulic pressure is controlled by the hydraulic control valve 29. The actual advance amount (actual valve timing) is controlled.

Next, the configuration of the variable valve timing mechanism 18 will be described with reference to FIG. A housing 31 of the variable valve timing mechanism 18 is fastened and fixed with bolts 32 to a sprocket 14 rotatably supported on the outer periphery of the intake side camshaft 16. Thereby, the rotation of the crankshaft 12 is transmitted to the sprocket 14 and the housing 31 through the timing chain 13, and the sprocket 14 and the housing 31 are rotated in synchronization with the crankshaft 12.

  On the other hand, the intake side cam 16 is rotatably supported by a cylinder head 33 and a bearing cap 34, and a rotor 35 is fastened and fixed to one end portion of the intake side cam shaft 16 with a bolt 37 via a stopper 36. . The rotor 35 is accommodated in the housing 31 so as to be relatively rotatable.

  As shown in FIGS. 4 and 5, a plurality of fluid chambers 40 are formed inside the housing 31, and each fluid chamber 40 is delayed from the advance chamber 42 by a vane 41 formed on the outer peripheral portion of the rotor 35. It is partitioned into a corner chamber 43. Seal members 44 are respectively attached to the outer periphery of the rotor 35 and the outer periphery of the vane 41, and each seal member 44 is urged by the leaf spring 45 in the outer peripheral direction. Thus, the gap between the outer circumferential surface of the rotor 35 and the inner circumferential surface of the housing 31 and the gap between the outer circumferential surface of the vane 41 and the inner circumferential surface of the fluid chamber 40 are sealed by the seal member 44.

  As shown in FIG. 3, an annular advance groove 46 and a retard groove 47 formed on the outer peripheral portion of the intake side camshaft 16 are respectively connected to predetermined ports of the hydraulic control valve 29, and oil is generated by the power of the engine 11. By driving the pump 28, the oil pumped up from the oil pan 27 is supplied to the advance groove 46 and the retard groove 47 through the hydraulic control valve 29. The advance oil passage 48 connected to the advance groove 46 passes through the inside of the intake camshaft 16 and communicates with an arcuate advance oil passage 49 (see FIG. 4) formed on the left side surface of the rotor 35. The arcuate advance oil passage 49 communicates with each advance chamber 42. On the other hand, the retarding oil passage 50 connected to the retarding groove 47 penetrates the inside of the intake side camshaft 16 to an arc-like retarding oil passage 51 (see FIG. 5) formed on the right side surface of the rotor 35. The arc retarded oil passage 51 is formed so as to communicate with each other, and communicates with each retarded angle chamber 43.

  In a state where the hydraulic pressure higher than a predetermined pressure is supplied to the advance chamber 42 and the retard chamber 43, the vane 41 is fixed by the hydraulic pressure of the advance chamber 42 and the retard chamber 43, and the housing 31 is rotated by the rotation of the crankshaft 12. The rotation is transmitted to the rotor 35 (vane 41) through the oil, and the intake side camshaft 16 is rotationally driven integrally with the rotor 35. During engine operation, the intake side cam with respect to the crankshaft 12 is controlled by controlling the hydraulic pressure in the advance chamber 42 and the retard chamber 43 by the hydraulic control valve 29 to rotate the housing 31 and the rotor 35 (vane 41) relative to each other. The valve timing of the intake valve is varied by controlling the rotation phase of the shaft 16 (hereinafter referred to as “cam shaft phase”). The sprocket 14 accommodates a torsion coil spring 55 (see FIG. 3) that assists the hydraulic pressure that causes the rotor 35 to relatively rotate in the advance angle direction by the spring force during the advance angle control.

  As shown in FIGS. 4 and 5, stopper portions 56 for restricting the relative rotation range of the rotor 35 (vane 41) with respect to the housing 31 are formed on both side portions of any one vane 41. The portion 56 regulates the most retarded angle phase and the most advanced angle phase of the cam shaft phase. Further, the lock pin accommodation hole 57 formed in the vane 41 accommodates a lock pin 58 for locking the relative rotation between the housing 31 and the rotor 35 (vane 41). By fitting into the provided lock hole 59 (see FIG. 3), the displacement angle of the cam shaft is locked at a predetermined lock position. This lock position is set to a suitable position at the time of starting, for example, at the most retarded position.

  During engine operation, the ECU 21 detects the actual valve timing that calculates the actual valve timing VT of the intake valve (actual advance angle position of the intake camshaft 16) based on the output signals of the crank angle sensor 20 and the cam angle sensor 19. It functions as a means, and calculates the target valve timing VTT of the intake valve (target advance angle position of the intake camshaft 17) based on the output of various sensors that detect the engine operating state such as the intake pressure sensor 22 and the water temperature sensor 23. Functions as a target valve timing setting means. Then, the ECU 21 calculates a feedback correction amount based on the deviation between the target valve timing VTT and the actual valve timing VT so that the actual valve timing VT of the intake valve matches the target valve timing VTT, and performs learning execution to be described later. When the condition is satisfied, the holding duty value (holding control amount) for maintaining the actual valve timing VT at the current position is learned, and the feedback correction amount is added to the holding duty value to obtain the control duty value (control amount). The hydraulic control valve 29 is feedback controlled. This function functions as a control amount calculation means and a hydraulic pressure control means in the claims. In this way, by controlling the hydraulic control valve 29 in a feedback manner, the hydraulic pressure in the advance chamber 42 and the retard chamber 43 is controlled to relatively rotate the housing 31 and the rotor 35, thereby changing the cam shaft phase. Thus, the actual valve timing VT of the intake valve is matched with the target valve timing VTT.

  Thereafter, when the engine 11 is stopped, if the engine speed is reduced, the discharge pressure of the oil pump 28 is reduced, so that the hydraulic pressure in the advance chamber 42 and the retard chamber 43 is reduced. As a result, the hydraulic pressure in the unlocking hydraulic chamber 65 (the hydraulic pressure in the advance chamber 42) and the hydraulic pressure in the lock hole 59 (hydraulic pressure in the retard chamber 43) are reduced, and the spring force of the spring 62 is reduced to these hydraulic pressures. When it is overcome, the lock pin 58 protrudes and fits into the lock hole 59 by the spring force of the spring 62. However, in order for the lock pin 58 to be fitted into the lock hole 59, it is a condition that both positions are coincident with each other, that is, the cam shaft phase is coincident with the lock position.

  When the engine 11 stops, the engine rotational speed (the rotational speed of the oil pump 28) decreases and the hydraulic pressure decreases, so that the camshaft phase naturally changes to the retard side due to the load torque of the camshaft 16. In the process, as shown in FIG. 6, the lock pin 58 is fitted into the lock hole 59 to lock the camshaft phase at the lock position.

As described above, the actual advance amount (actual valve timing) of the intake camshaft 16 is controlled by controlling the hydraulic control valve 29 based on the control duty value (control amount). The control duty value of the hydraulic control valve 29 is calculated based on the feedback correction amount based on the deviation between the target valve timing and the actual valve timing and the holding duty value. Here, the holding duty value is a duty value when the displacement speed (advance speed) of the valve timing becomes 0, that is, a duty value for maintaining the current valve timing.

  This holding duty value varies depending on manufacturing tolerances of the variable valve timing mechanism 18 and the hydraulic control valve 29, changes with time, oil temperature, engine speed, and the like. If the holding duty value changes, the actual valve timing cannot be controlled with high accuracy, and the accuracy of the variable valve timing control may be reduced. For this reason, it is necessary to learn the holding duty value according to the engine state at that time. As an example of such a learning technique, when the deviation between the target valve timing and the actual valve timing is equal to or greater than a predetermined value and the target valve timing and the actual valve timing do not change respectively for a predetermined time, Some have learned the control duty value as the holding duty value.

  However, in this technique, since the learning execution condition is that the state in which the target valve timing and the actual valve timing do not change continues for a predetermined time, for example, the responsiveness of the variable valve timing mechanism 18 decreases for some reason. In such a case, the actual valve timing is delayed to converge to the target valve timing, and the learning execution condition is delayed to be satisfied. Due to the mismatch between the actual valve timing and the target valve timing, There is a risk of problems such as insufficient torque.

  This prior art will be specifically described with reference to FIG. Here, FIG. 6A is a time chart showing the behavior of the actual advance amount (actual valve timing) with respect to the step change of the target advance amount (target valve timing). The actual advance amount is indicated by a solid line. The target advance amount is indicated by a one-dot chain line. 6B shows the behavior of the holding duty value A, and FIG. 6C shows the behavior of the feedback correction amount B based on the deviation between the target advance amount and the actual advance amount. FIG. 6D shows the behavior of the control duty value (A + B) obtained by adding the holding duty value A and the feedback correction amount B.

  First, when the target advance amount changes stepwise at time to in FIG. 6, the deviation between the target advance amount and the actual advance amount increases with the change, and is calculated based on the deviation. The feedback correction amount B increases [see FIG. 6 (c)]. The feedback correction amount B increases to some extent, but decreases as the deviation between the target advance amount and the actual advance amount becomes smaller. However, at this time, if the holding duty value A is greatly deviated from the appropriate value, the control duty value (A + B) becomes smaller as the feedback correction amount B based on the deviation decreases, so the actual advance amount is set to the target amount. It decreases without reaching the advance amount. At this time, since the deviation between the target advance amount and the actual advance amount increases, the feedback correction amount B based on the deviation also increases little by little. However, the actual advance amount is stable at a position deviating from the target advance amount. May end up. Even in such a state, the learning execution condition is satisfied and the learning of the holding duty value A is executed at the time t1 when the state in which the target advance angle amount and the actual advance angle amount do not change each continues for a predetermined time. The control duty value (A + B) at t1 becomes the learning value of the holding duty value A. As a result, when the holding duty value A is updated, the control duty value (A + B) increases rapidly, and the actual advance amount starts to change toward the target advance amount.

  As described above, in the conventional technique, the learning execution condition is not satisfied and the learning value of the holding duty value A is not updated until the state in which the target advance angle amount and the actual advance angle amount do not change continues for a predetermined time. During this period, the deviation between the target advance amount and the actual advance amount is maintained at a large level. As a result, the torque is insufficient due to the mismatch between the actual advance amount and the target advance amount. There is a possibility that this problem may occur. In addition, if the learning execution condition is satisfied later, the learning execution condition is less frequently satisfied. Therefore, the learning frequency of the holding duty value A is decreased, and the learning accuracy of the holding duty value A is decreased. There is also the problem of doing.

  As a countermeasure, in this embodiment, it is determined whether or not the learning execution condition for the holding duty value (holding control amount) is satisfied based on the change direction of the actual advance amount, and the learning execution condition is satisfied. The holding duty value is learned when it is determined.

  A method for learning the holding duty value of this embodiment will be described with reference to the time chart of FIG. As in FIG. 6, FIG. 7A is a time chart showing the behavior of the actual advance amount (actual valve timing) with respect to the step change of the target advance amount (target valve timing). A solid line indicates the target advance amount by a one-dot chain line. FIG. 7B shows the behavior of the holding duty value A, and FIG. 7C shows the behavior of the feedback correction amount B based on the deviation between the target advance amount and the actual advance amount. FIG. 7D shows the behavior of the control duty value (A + B) obtained by adding the holding duty value A and the feedback correction amount B. In FIG. 7, the description overlapping with FIG. 6 will be described briefly.

  First, when the target advance amount changes stepwise at time to in FIG. 7, the deviation between the target advance amount and the actual advance amount increases with the change, and is calculated based on the deviation. The feedback correction amount B increases [see FIG. 7 (c)]. This feedback correction amount B is decreased when the deviation between the target advance amount and the actual advance amount becomes small (near time t1).

  When the responsiveness of the variable valve timing mechanism 18 is lowered for some reason, the actual advance amount changes in a direction approaching the target advance amount immediately after the change of the target advance amount. Before the advance amount reaches the target advance amount, the actual advance amount may change in a direction away from the target advance amount. Therefore, in this embodiment, it is monitored whether or not the change direction of the actual advance amount has changed in a direction away from the direction approaching the target advance amount, and the change direction of the actual advance amount deviates from the target advance amount. At the time point t1 when the change in direction is detected, the learning execution condition is satisfied, the learning of the holding duty value A is executed, and the control duty value (A + B) at the time point t1 becomes the learning value of the holding duty value A. . As a result, when the holding duty value A is updated at time t2, the control duty value (A + B) temporarily increases rapidly, and the actual advance amount starts to change rapidly toward the target advance amount.

  In this way, in this embodiment, the holding duty value A is learned at the time t1 when it is detected that the change direction of the actual advance amount has changed in the direction away from the target advance amount. As described above, it is possible to learn the holding duty value A without waiting until the state in which the target advance angle amount and the actual advance angle amount do not change continues for a predetermined time, and the holding duty value A is learned relatively early. It becomes possible to do.

  Hereinafter, a program for learning the holding duty value of this embodiment will be described with reference to FIG. This program is executed by the ECU 21 at a predetermined cycle, and plays a role as learning means in the claims.

  When the program of FIG. 8 is started, first, in step S101, the engine operating state is detected. The engine operating state is detected based on signals from various sensors such as an intake pressure sensor 22, a water temperature sensor 23, and a throttle sensor 24, for example.

  Thereafter, the process proceeds to step S102, where it is determined whether or not the target advance amount has changed relatively rapidly depending on whether or not the change amount of the target advance amount is equal to or greater than a predetermined value. In the region where the amount is less than the predetermined value (region where the target advance amount does not change or changes slowly), it is not necessary to change the actual advance amount with good response. Note that it may be determined whether or not the target advance amount has changed relatively abruptly based on whether or not the difference between the target advance amount and the actual advance amount is a predetermined value or more.

  On the other hand, when it is determined in step S102 that the amount of change in the target advance amount is equal to or greater than the predetermined value (when the target advance amount changes relatively abruptly), the change in the target advance amount is changed. Accordingly, since it is necessary to change the actual advance amount with good response, the process proceeds to step S103, and the change speed of the actual advance amount is detected. At this time, in order to detect the change rate of the actual advance angle amount, for example, the actual advance angle amount is detected every predetermined time, and the advance angle amount is divided by the predetermined time.

  After detecting the change rate of the actual advance angle amount, the process proceeds to step S104, and the actual advance angle amount is determined depending on whether the change rate of the actual advance angle amount is less than a predetermined value “0” (whether it is a negative value or a positive value). The direction of change is determined. Here, it is determined whether or not the actual advance amount changes in a direction in which the difference between the target advance amount and the actual advance amount increases. If the actual advance amount changes in a direction that increases the difference between the target advance amount and the actual advance amount, the holding duty value is likely to deviate from the appropriate value. Is established, the process proceeds to step S105, and learning of the holding duty value is executed. At this time, based on the feedback correction amount (control amount) calculated based on the deviation between the target advance amount and the actual advance amount, the previous hold duty value (before this program is executed) is corrected. The learning value of the new holding duty value is used. That is, the current control duty value obtained by adding the feedback correction amount calculated based on the deviation between the target advance angle amount and the actual advance angle amount during learning and the hold duty value before correction is set as a new hold duty. Learn as a value.

  In step S104, the process may proceed to step S105 when a predetermined time elapses when the change rate of the actual advance amount is equal to or less than a predetermined value.

  On the other hand, if it is determined in step S104 that the change rate of the actual advance amount is equal to or greater than the predetermined value “0”, it is determined that the actual advance amount is changing toward the target advance amount, and the process proceeds to step S106. It is determined whether or not the elapsed time after the change in the target advance amount has exceeded a predetermined time necessary for the actual advance amount to reach the target advance amount. If it is determined in step S106 that the elapsed time after the change in the target advance amount is equal to or shorter than the predetermined time, it is determined that the actual advance amount is still changing toward the target advance amount. Then, the process returns to step S103.

  On the other hand, if it is determined in step S106 that the elapsed time after the change in the target advance amount has exceeded the predetermined time, the holding duty value is set to an appropriate value and the actual advance amount becomes the target advance amount. It is determined that the program has been reached, and the program is terminated.

  Note that, when it is determined in step S106 that the elapsed time after the change in the target advance amount has exceeded a predetermined time, the holding duty value may be corrected for learning as in step S105 described above.

  In the present embodiment described above, it is determined whether or not the actual actual advance amount changes in a direction in which the deviation between the target advance amount and the actual advance amount increases, and if the determination is affirmed, learning is performed. Since the execution duty is satisfied and the holding duty value is learned, the holding duty value is not waited until the target advance angle amount and the actual advance angle amount do not change, respectively, for a predetermined period of time as in the conventional case. The value can be learned. As a result, even if the holding duty value is deviated from an appropriate value, the holding duty value can be learned and corrected at an early stage. This shortens the period during which the deviation between the target advance angle amount and the actual advance angle amount is large, thereby reducing problems such as torque shortage and emission deterioration caused by a mismatch between the actual advance angle amount and the target advance angle amount. can do.

  In this embodiment, it is determined whether or not the actual advance amount changes in the direction in which the difference between the target advance amount and the actual advance amount increases, but this is shown in FIGS. 6 and 7. As described above, if the holding duty value is not set to an appropriate value, the difference between the target advance angle amount and the actual advance angle amount decreases and then changes so as to increase. The behavior in the changing direction of the actual advance amount may be detected. Even in this case, even if the holding duty value is not set to an appropriate value, the holding duty value can be learned and corrected early.

  6 and 7, the case where the target advance amount is larger than the actual advance amount has been described. However, the present embodiment can also be applied when the target advance amount is smaller than the actual advance amount. Even in this case, if the holding duty value is not set to an appropriate value, the difference may increase after the difference between the target advance angle amount and the actual advance angle amount decreases. Specifically, since the change rate of the actual advance angle amount changes from a negative value to a positive value, the holding duty value is learned when the change rate of the actual advance angle amount is equal to or greater than a predetermined value “0” in the above program. It is good to do so.

  In this embodiment, when the change rate of the actual advance amount is a positive value, it means that the actual advance amount advances to the advance side, and when the change rate of the actual advance amount is a negative value. Means that the actual advance amount advances toward the retard side. If the target advance amount is larger than the actual advance amount, it means that the target advance amount is set to the advance side of the actual advance amount, and the target advance amount is the actual advance amount. Is smaller than the actual advance amount, it means that the target advance amount is set to the retard side.

  In this embodiment, when learning the holding duty value based on the change direction of the actual advance angle amount, the change direction of the actual advance angle amount is determined based on whether the change speed of the actual advance angle amount is a positive value or a negative value. However, the change direction of the actual advance angle amount may be determined from the locus of the actual advance angle amount. That is, the actual advance amount may be detected, and the change direction of the actual advance amount may be determined based on the actual advance amount trajectory.

  Although the present embodiment is an embodiment in which the present invention is applied to intake side variable valve timing control, it goes without saying that the present invention may be applied to exhaust side variable valve timing control.

It is a schematic block diagram of the whole control system in one Example of this invention. It is a figure explaining the structure of a cam angle sensor. It is a longitudinal cross-sectional view of a valve timing control device. It is sectional drawing shown along the AA line of FIG. It is sectional drawing shown along the BB line of FIG. It is a time chart explaining the learning method of the holding | maintenance duty value in a prior art. It is a time chart explaining the learning method of the holding | maintenance duty value in a present Example. It is a flowchart of the program which learns the holding | maintenance duty value in a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Engine 12 ... Crankshaft 16 ... Intake camshaft 17 ... Exhaust camshaft 18 ... Variable valve timing mechanism 19 ... Cam angle sensor 20 ... Crank angle sensor 21 ... ECU (Hydraulic control means, target valve timing setting means, actual valve timing) Detection means, control amount calculation means, learning means)

Claims (6)

A variable valve timing mechanism that changes the valve timing on the intake side and / or the exhaust side of the internal combustion engine using hydraulic pressure as a drive source;
Hydraulic control means for controlling the hydraulic pressure for driving the variable valve timing mechanism;
Target valve timing setting means for setting a target valve timing based on the operating state of the internal combustion engine;
Actual valve timing detection means for detecting actual valve timing (hereinafter referred to as “actual valve timing”);
A control amount calculating means for calculating a control amount of the hydraulic control means based on a deviation between the target valve timing and the actual valve timing and a holding control amount for maintaining the actual valve timing at a current position;
The valve timing of the internal combustion engine that controls the hydraulic pressure that drives the variable valve timing mechanism by the hydraulic pressure control means so that the actual valve timing matches the target valve timing based on the control quantity calculated by the control quantity calculation means. In the control device,
Learning means for learning the holding control amount;
The learning means determines whether or not a learning execution condition for learning the holding control amount is satisfied based on a change direction of the actual valve timing detected by the actual valve timing detection means, and the learning execution condition is A valve timing control device for an internal combustion engine, which learns the holding control amount when it is determined that the relationship is established.   The learning means determines whether or not the actual valve timing has changed in a direction in which a deviation between the target valve timing and the actual valve timing increases as the learning execution condition, and when the determination is affirmed 2. The valve timing control apparatus for an internal combustion engine according to claim 1, wherein it is determined that the learning execution condition is satisfied.   The learning means determines, as the learning execution condition, whether or not the change direction of the actual valve timing has changed in a direction in which the deviation increases after the deviation between the target valve timing and the actual valve timing decreases. 2. The valve timing control apparatus for an internal combustion engine according to claim 1, wherein when the determination is made and the determination is affirmative, it is determined that the learning execution condition is satisfied.   The valve timing control device for an internal combustion engine according to any one of claims 1 to 3, wherein the learning execution condition is that at least one condition is that the actual valve timing changes.   The learning means determines the change direction of the actual valve timing based on whether or not the change speed of the actual valve timing detected by the actual valve timing detection means is a positive value or a negative value. 5. The valve timing control device for an internal combustion engine according to any one of 1 to 4.   6. The learning device according to claim 1, wherein the learning unit learns and corrects the holding control amount based on a control amount calculated in accordance with a deviation between the target valve timing and the actual valve timing. A valve timing control device for an internal combustion engine according to claim 1.

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